Nebulized riclinoctaose mitigates ovalbumin-induced allergic asthma by attenuating mast cell activation

Allergic asthma is an inflammatory airway disease in which mast cells play a key role in its pathogenesis. Riclinoctaose (Rios), an octasaccharide composed of glucose and galactose, has been reported to modulate macrophage polarization in renal ischemia-reperfusion injury. This study investigates the effects of nebulized Rios in an ovalbumin (OVA)-induced allergic asthma model. Nebulized Rios significantly reduced airway hyperresponsiveness (AHR), inflammatory cell infiltration, pulmonary fibrosis, and mucus production in OVA-treated mice. Additionally, Rios suppressed lung inflammatory cytokine production and protected against OVA-induced oxidative injury. In bronchoalveolar lavage fluid (BALF), Rios decreased the number of neutrophils and macrophages, as well as serum immunoglobulin E (IgE) and interleukin-4 (IL-4) levels. Metabolomics analysis using ¹H NMR showed significant changes in the lung metabolic profile of OVA-induced asthma mice, which were partially reversed by Rios treatment. Confocal laser microscopy (CLM) revealed that fluorescently labeled Rios specifically binds to mast cell membranes. In vitro, Rios reduced degranulation and inflammatory responses in mast cells RBL-2H3 following anti-Dinitrophenyl-Immunoglobulin E (anti-DNP-IgE) sensitization and anti-Dinitrophenyl-Bovine Serum Albumin (anti-DNP-BSA) stimulation. These results suggest that Rios has therapeutic potential for allergic asthma, likely through the modulation of mast cell degranulation and mediator release.